1. Field of the Invention
The present invention relates to a scrap charger designed to manipulate scrap during conveyance to an electric furnace used in a steel making process and, more particularly, to the construction of such a scrap charger to promote an organized flow of scrap from a storage bunker into a scrap delivery chute communicating with an electric arc furnace.
2. Description of the Prior Art
It is known in the art to supply scrap to steel making furnaces by diverse modes of transportation. A furnace such as a basic oxygen furnace may receive a scrap charge transported by an overhead crane in a scrap bucket. To lessen the demand for an overhead crane, a conveyor or sequentially arranged conveyors can be used to convey scrap to the furnace, but the conveyor installation occupies space in the facility which can be extensive along a course that becomes congested in and about the site of the steel making furnace. Rail cars may be used to shuttle scrap buckets between a scrap storage area and the steel-making furnace for the charging of scrap. Other steel making furnaces such as an electric arc furnace may directly communicate utilize a scrap charger to supply scrap from an integral scrap storage bunker or hopper.
In my patent application Ser. No. 09/739,851, there is disclosed a scrap charging apparatus for an electric arc furnace using diverging end walls extending between converging side walls of a scrap holding bunker to provide an impetus in the bunker for scrap flow to an underlying scrap delivery chute. The scrap delivery chute includes an elongated scrap-carrying trough having a greater width than the exit width for scrap from the scrap holding bunker. A ram is controlled by a drive to incrementally advance scrap along the scrap delivery chute for introducing successive preselected volumes of scrap to a charging opining for an electric arc furnace. The scrap holding bunker and scrap delivery chute are engaged and supported by a superstructure at an elevated and lateral spaced location from the electric arc furnace. The scrap-carrying trough terminates with the provision of a water-cooled trough section that is extendable through a charging opening in an upper furnace wall of the electric arc furnace for charging scrap and retracted for servicing of the furnace. The present invention seeks to alleviate the possibility of a scrap jam occurring in the vicinity of the transition of scrap flow from a generally vertical flow to a generally horizontal flow and which can be adversely influenced by the superimposed weight of the column of scrap bounded by the diverging end walls and converging side walls of a scrap holding bunker.
It is an object of the present invention to provide a transport vehicle constructed for displacing a scrap charger supported thereon between a scrap charging position wherein a horizontal scrap deliverly chute extends into an electric arc furnace for the charging of scrap and an inoperative position wherein the scrap delivery chute is remotely spaced from the electric furnace to allow servicing of the electric arc furnace and or tapping of a melt from the furnace.
It is another object of the present invention to provide a scrap charger to maintain a flow of scrap particularly in an area of transition underneath a storage bunker where the scrap must advance from a generally vertical columnar flow to a generally horizontally subdivided fraction advanced intermittently along a generally horizontally extending delivery chute communicating with an electric arc furnace.
It is a further object of the present invention to provide a scrap charger construction to enable subdividing layers of scrap in such a fashion that a scrap advancing force by a ram always remains sufficient to move the scrap through a throat opening into the horizontal feed chute by controlling the size of the throat opening.
It is a further object of the present invention to provide a scrap charger to maintain a flow of scrap particularly to an area of transition underneath a storage bunker where the scrap must advance from a generally vertical columnar flow to a generally horizontally subdivided fraction by providing the storage bunker with an elongated end wall section inclined to the horizontal at an acute angle selected to utilize the force of gravity to advance scrap laterally into the generally vertical columnar flow of scrap and thereby reduce the compacting forces arising out of the height of the scrap column in the storage bunker.
According to the present invention there is provided a scrap charging apparatus for an electric arc furnace, the scrap charging apparatus including the combination of a scrap holding bunker having a scrap fall space extending to an underlying scrap discharge opening, a scrap delivery chute including a generally horizontal feed chute section having a scrap jam relief gate at a throat opening for receiving scrap from the scrap discharge opening, the scrap jam relief gate being displaceable between an operating position establishing a desired flow of scrap passing the throat opening from the scrap holding bunker and a second position for passage of scrap impeded by the scrap jam relief gate at the operating position, and a ram controlled by a drive to advance scrap from the scrap discharge opening through the throat opening for delivery from the scrap delivery chute.
According to a further aspect of the present invention there is provided a scrap charging apparatus for an electric arc furnace, said scrap charging apparatus including the combination of a scrap holding bunker having a scrap fall space bounded by spaced apart side walls and a front end wall spaced by a scrap delivery opening from a back end wall and the back end wall essentially including an elongated inclined wall section sloping to the horizontal toward the scrap delivery opening at an acute angle sufficient in magnitude for utilizing the force of gravity to promote lateral advancing movement of scrap along the elongated inclined wall section into the scrap delivery opening and thereby reduce vertical loading on scrap entering the scrap discharge opening, a scrap delivery chute including a generally horizontal elongated feed chute section extendable through a charging opening of an electric arc furnace for charging of scrap received from the scrap discharge opening, and a ram controlled by a drive to advance scrap from the scrap delivery chute into the electric arc furnace.
According to a still further aspect of the present invention there is provided a scrap charging apparatus for an electric arc furnace, the scrap charging apparatus including the combination of a scrap holding bunker having a scrap fall space extending to an underlying scrap discharge opening, a scrap delivery chute including a generally horizontal elongated feed chute section extendable through a charging opening of an electric arc furnace for charging of scrap received from the scrap discharge opening, a transport vehicle supporting the scrap delivery chute for movement between a scrap charging position wherein the generally horizontal elongated feed chute section extends through a charging opening into an electric arc furnace and an inoperative position, with or without corresponding movement of the scrap holding bunker, wherein the horizontal elongated feed chute section is withdrawn from the charging opening for taping of the electric arc furnace, a structure for supporting the transport vehicle at a laterally spaced location from the electric arc furnace, and a ram controlled by a drive to advance scrap from the scrap delivery chute into the electric arc furnace.